Quote:
But if you can't map them in the expose preferences then I don't think OS X is seeing them at all


You may be on to something here.

Have you tried pulling out any intellimouse software on the Mac, so that it reverts to the base OS X driver? Then open the Expose control panel and see if it shows Mouse buttons above the third one.

I uae a Logitech MX 900 on my Powerbook, and never bothered with any specific mouse drivers, since OS X just saw all the buttons and used them.